A 2.388-mi section of four-lane highway in Louisville, Ky., was selected for an experimental fly ash concrete pavement installation. The project was divided into three sections: a control section and two experimental sections containing 94 and 140 lb of fly ash per cubic yard, respectively. The solid-volume of fly ash in excess of that required to replace one sack of cement was considered as fine aggregate. The water was adjusted to provide a slump of approximately 2½ in., and an air-entraining admixture was proportioned at the mixer to provide an air content of approximately 4.5 percent.

Beams and cylinders were cast from various random mixtures within each section. Flexural and compressive strength tests were made at 3, 7 and 28 days, and 3, 6 and 12 mo. Beams were also cast for freeze and thaw testing. Test results to date are included in the report, as well as a description of construction procedures and mix design methods.

Early strengths for concrete placed in the experimental sections were lower than those for concrete placed in the control section. On the basis of limited 3-mo age compressive strength tests, a gain in strength at later ages was achieved through the use of fly ash. No reduction in water requirement was gained through the addition of fly ash.

Report Date


Report Number

No. 231

Digital Object Identifier



Presented at the 43rd ANNUAL MEETING (January 13-17, 1964).

Also identified as Highway Research Board, Record 73, 1965.